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| Titel |
Long term measurements of sulfur dioxide, nitrogen dioxide, ammonia, nitric acid and ozone in Africa using passive samplers |
| VerfasserIn |
M. Adon, C. Galy-Lacaux, V. Yoboué, C. Delon, J. P. Lacaux, P. Castera, E. Gardrat, J. Pienaar, H. Ourabi, D. Laouali, B. Diop, L. Sigha-Nkamdjou, A. Akpo, J. P. Tathy, F. Lavenu, E. Mougin |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 15 ; Nr. 10, no. 15 (2010-08-10), S.7467-7487 |
| Datensatznummer |
250008699
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| Publikation (Nr.) |
 copernicus.org/acp-10-7467-2010.pdf |
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| Zusammenfassung |
| In this paper we present the long term monitoring of ambient gaseous
concentrations within the framework of the IDAF (IGAC-DEBITS-AFRICA)
program. This study proposes for the first time an analysis of long-term
inorganic gas concentrations (1998 to 2007) of SO2, NO2,
HNO3, NH3 and O3, determined using passive samplers at seven
remote sites in West and Central Africa. Sites are representative of several
African ecosystems and are located along a transect from dry savannas-wet
savannas-forests with sites at Banizoumbou (Niger), Katibougou and Agoufou
(Mali), Djougou (Benin), Lamto (Cote d'Ivoire), Zoetele (Cameroon) and
Bomassa (Congo). The strict control of measurement techniques as well as the
validation and inter-comparison studies conducted with the IDAF passive
samplers assure the quality and accuracy of the measurements. For each type
of African ecosystem, the long term data series have been studied to
document the levels of surface gaseous concentrations. The seasonal and
interannual variability have also been analyzed as a function of emission
source variations. We compared the measured West and Central African gas
concentrations to results obtained in other parts of the world. Results show
that the annual mean concentrations of NO2, NH3, HNO3
measured in dry savannas are higher than those measured in wet savannas and
forests that have quite similar concentrations. Annual mean NO2
concentrations vary from 0.9±0.2 in forests to 2.4±0.4 ppb in the
dry savannas, NH3 from 3.9±1.4 to 7.4±0.8 ppb and HNO3
from 0.2±0.1 to 0.5±0.2 ppb. Annual mean O3 and SO2
concentrations are lower for all ecosystems and range from 4.0±0.4 to
14.0±2.8 and from 0.3±0.1 to 1.0±0.2 ppb, respectively. A
focus on the processes involved in gas emissions from dry savannas is
presented in this work, providing explanations for the high concentrations
of all gases measured at the three dry savannas sites. At these sites,
seasonal concentrations of all gases are higher in the wet season.
Conversely, concentrations are higher in the dry season in the wet savannas.
In forested regions, we measure no significant difference between wet and
dry seasons. This unique database of long term gases concentrations
monitoring is available at: http://medias.obs-mip.fr/idaf/. |
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